The Doctrine of Estoppel in Nigerian Evidence Law: Types, Operation and Limits

A developer tells a farmer in Ogun State: “Do not worry about the fence. Build your house right up to the boundary. I will never enforce my right to the fence line.” The farmer, relying on this representation, spends his savings building up to the boundary. Three years later, the developer sells the land to a new buyer who immediately sues the farmer for trespass. Can the new buyer enforce the fence line?

The doctrine of estoppel says no, or at least it makes it very difficult. The developer made a representation. The farmer acted on it to his detriment. The law will not now allow the developer (or those claiming through the developer) to resile from that representation. The farmer is protected not because he has a legal title to the extra space, but because the law prevents the other side from asserting the legal title they might otherwise have.

This is estoppel in action. It is one of the most practically important doctrines in Nigerian law, appearing in land disputes, contract cases, matrimonial proceedings, and criminal law. And yet it is also one of the most misunderstood. This article explains what estoppel is, its types under the Evidence Act 2011, how each type operates, and its limits.

Etymology and General Meaning

The word estoppel comes from the French word “estoppel,” meaning to stop. Estoppel generally implies that a person’s own act or acceptance prevents them from asserting a position inconsistent with what they previously represented or accepted.¹

In Nigerian evidence law, estoppel is both a rule of evidence and a substantive doctrine, and the controversy about which it truly is has not been fully resolved. To the extent that estoppel is found in sections 169 to 174 of the Evidence Act 2011, it is a rule of evidence. But estoppel is also found in other branches of law, including contract, land law, and matrimonial causes, where it operates as a substantive rule. This dual character is part of what makes the doctrine complex.

In Oyerogba v Olaopa,² the court held that when a person has clearly made a representation to another and that other person has acted on it and had their position altered, the person who made the representation is precluded from denying the representation. That is the core of estoppel.

Coke classified estoppel into estoppel in pais (by conduct), estoppel in writing, and estoppel by matter of record. In modern times, the classification recognises estoppel by representation, promissory estoppel, estoppel by deed, and estoppel per rem judicatam or res judicata.³

Estoppel as a Shield, Not a Sword

One of the most fundamental principles of estoppel in Nigerian law is that it operates as a shield, not a sword.

A shield means that estoppel can only be used defensively. It is pleaded by a defendant to defeat a claim made against them. The farmer in the opening illustration uses estoppel as a shield to defeat the trespass claim.

A sword would mean using estoppel offensively, as the basis of an affirmative claim. Estoppel cannot generally be used this way. You cannot sue someone simply because they said something that estops them. Estoppel prevents denial of a position; it does not create new rights.

There is a limited exception. In Ukaegbu v Ugoji,⁴ the court held that in limited circumstances, estoppel can be pleaded in a statement of claim as a relevant fact. This is an exception rather than the rule, and students should state the general position (shield, not sword) before mentioning the exception.

The procedural consequence is important. Estoppel is generally pleaded in the statement of defence or in a reply to a defence. It is not necessary to use the word “estoppel.” It is sufficient if the facts establishing estoppel are clearly pleaded.

Estoppel by Representation

Estoppel by representation arises when a party makes a clear and unambiguous representation of fact to another party, that other party relies on the representation and changes their position as a result, and it would be inequitable to allow the representor to resile from the representation.

Three elements must be established.

First, the representation must be of fact, not of law. Representations of law do not ground estoppel by representation because everyone is presumed to know the law. A representation that “you are entitled to build up to this fence” is a representation of fact about what one is allowed to do. A representation that “the law allows you to do this” is a representation of law and does not ground estoppel.

Second, the representee must have relied on the representation. If the representee did not know about the representation, or if they would have acted in the same way regardless of it, there is no reliance and estoppel does not arise.

Third, the representee must have altered their position as a result. Simply receiving a representation without acting on it is insufficient. There must be some change of position, typically by doing something (like building) or refraining from doing something (like not taking alternative steps to protect a right) in consequence of the representation.

Estoppel by Deed

Estoppel by deed arises from a written instrument, particularly in the context of deeds and conveyances. Where a person executes a deed containing recitals of fact, they and their privies are estopped from asserting that the recited facts are false.

A recital is a clause in a deed that sets out the background facts giving rise to the transaction. If a deed of conveyance recites that the seller is the fee simple owner of the land, the seller cannot later claim they had no title to convey. The recital estops them.

This form of estoppel is particularly significant in Nigerian land law. Deeds of conveyance and deeds of assignment regularly contain recitals tracing the history of ownership. Those recitals bind the parties and their successors in title.

Promissory Estoppel

Promissory estoppel, also called equitable estoppel or estoppel by acquiescence, is a more modern development. It arises where a party makes a clear and unequivocal promise that they will not enforce a strict legal right, and the other party relies on that promise to their detriment.

The foundational authority for promissory estoppel in Nigerian law is the English case of Central London Property Trust v High Trees House Ltd,⁵ known as the High Trees case. The court held that a promise not to enforce a right will be binding in equity where the other party has relied on it.

The critical limitation of promissory estoppel is that it can only be used as a shield. In Ukaegbu v Ugoji,⁴ the Nigerian court confirmed this limitation. Promissory estoppel prevents the promisor from going back on their promise. It does not create a new cause of action in the promisee.

Whether the promisee must have suffered a detriment before promissory estoppel can be relied upon is debated. Some authorities require detriment. Others hold that reliance alone is sufficient.

We encounter promissory estoppel most often in the context of contract law in Nigeria, where it prevents strict enforcement of legal rights in circumstances where enforcement would be unconscionable.

Estoppel per Rem Judicatam: Res Judicata

This is the most practically significant form of estoppel and the one most frequently examined. Estoppel per rem judicatam, commonly called res judicata, prevents a party from relitigating an issue that has already been conclusively decided by a court of competent jurisdiction.

Section 169 of the Evidence Act 2011 provides that when a judgment of a competent court is directly in issue, the parties and their privies are estopped from relitigating the matter. The rationale is public policy: litigation must come to an end, and a party should not be vexed twice by the same claim.

The Four Requirements

Four conditions must be met before res judicata operates successfully.

The first requirement is sameness of parties. The parties in both proceedings must be the same, or they must be privies. Privies include privies in blood (ancestors and heirs), privies in law (executors and administrators), and privies in estate (devisees and purchasers). In McKenny v Chief Constable of West Midlands Police Force,⁶ the court held that what matters is the substance, not the label, of the parties’ connection.

The second requirement is sameness of issues. The issue decided in the earlier proceedings must be the same as the issue now being raised. This does not require that the cause of action be identical. The question is whether the same issue, the same material fact, is being put in dispute again.

The third requirement is finality of judgment. The earlier judgment must be final. An interim judgment, a judgment on a preliminary point, or a judgment that has been appealed against and reversed is not final for res judicata purposes. Consent judgments and default judgments can ground a successful plea because they are final. Judgments ordering a retrial, declaring a non-suit, or dismissing a suit for want of prosecution cannot ground estoppel.

A discharge and acquittal following a successful no-case submission in criminal proceedings is final and grounds a plea of res judicata. But a ruling that a prima facie case has been established is not final and cannot ground estoppel.

The fourth requirement is that the earlier judgment must have been delivered by a court of competent jurisdiction. A superior court of record is presumed to have jurisdiction until the contrary is shown. An inferior court is presumed to lack jurisdiction until jurisdiction is established. This means that when pleading res judicata based on an inferior court’s judgment, the defendant must plead not only the judgment but also the facts establishing that court’s jurisdiction.

Issue Estoppel Distinguished

Issue estoppel is a refinement of res judicata. Where an earlier judgment decided a specific issue, and that same issue arises in later proceedings between the same parties or their privies, the party against whom the issue was decided cannot relitigate it, even if the later proceedings involve a different cause of action. The classification of the proceedings as criminal or civil is irrelevant to this. The traditional understanding is that a single act can simultaneously ground both criminal and civil liability, since the two proceedings are structurally distinct: criminal liability is prosecuted by the State against the accused, while civil liability is claimed by the aggrieved private party, and neither proceeding bars the other as a matter of course. Indeed, where the same act constitutes both a felony and a civil wrong, the rule in Smith v Selwyn [1914] 3 KB 98 requires that criminal proceedings be disposed of first before a civil action can proceed. The practical consequence of this sequencing is that once a specific factual issue has been conclusively determined in the criminal proceedings, the party against whom it was decided cannot reopen that finding in the civil proceedings that follow. The doctrine fastens on the finality of the determination on the particular issue, not on the label of the forum or proceedings that produced it.

In McKenny v Chief Constable of West Midlands Police Force,⁶ the court confirmed that what matters for sameness of issue is the substance of the fact in dispute, not how the dispute is classified.

Res Judicata in Criminal Law

The constitutional rule against double jeopardy in section 36(9) of the 1999 Constitution is closely related to, but distinct from, res judicata in criminal cases. Section 36(9) provides that a person who has been tried and either convicted or acquitted cannot be tried again for the same offence or one with the same ingredients.

The defences of autrefois acquit and autrefois convict are the procedural expression of this rule. They are related to but not identical with estoppel per rem judicatam. The burden of establishing these special pleas lies on the accused.

In customary arbitration, the principles of estoppel apply where parties have voluntarily submitted to the arbitration, the arbitrators were empowered to decide, and a decision was reached and published. Publication of the award is required for estoppel to operate, but oral publication is sufficient if it is adequately proved.

The Relationship Between Estoppel and Res Judicata

All res judicata is a form of estoppel, but not all estoppel is res judicata. The similarity is that a successful plea of either estoppel or res judicata prevents the claim from being sustained. The dissimilarity is significant: estoppel is a form of admission and binds the party who made the representation or took the inconsistent position. Res judicata does not only bind the party involved; it also precludes the court from exercising jurisdiction over the matter again. Res judicata therefore has a wider effect than personal estoppel.

Stare decisis is another related concept but fundamentally different. Stare decisis binds future courts, not just the parties to a suit. Estoppel binds the parties. Res judicata binds the parties and the court. All three prevent reconsideration of decided matters but in different ways and by different mechanisms.

A Quick Reference Table

Key Cases

Oyerogba v Olaopa (1998) 12 NWLR (Pt. 578) 353 The court held that when a person makes a representation and another acts on it and changes their position, the representor is precluded from denying the representation. Core statement of estoppel by representation in Nigeria.

Ukaegbu v Ugoji The court held that in limited circumstances, estoppel may be pleaded as a relevant fact in a statement of claim. This is the exception to the general rule that estoppel is a shield only.

McKenny v Chief Constable of West Midlands Police Force (1980) QB 283 The court held that for sameness of issues in res judicata, what matters is the substance of the fact in dispute, not how the proceedings are classified.

Central London Property Trust v High Trees House Ltd (1947) KB 130 The foundational authority for promissory estoppel, adopted in Nigerian courts. A clear promise not to enforce a right is binding in equity where the promisee has relied on it.

Madukolu v Nkemdilim (1962) 2 SCNLR 341 The court defined when a court can be said to have jurisdiction: proper constitution, competence as to subject matter, proper commencement of proceedings, and fulfilment of conditions precedent. Jurisdiction is a prerequisite for res judicata.

Problem Question Framework

When a problem question involves a party attempting to assert a legal right that contradicts a position they previously took, apply this framework.

First, identify the type of estoppel most applicable. Is it estoppel by representation (a statement of fact relied upon)? Estoppel by deed (a recital in an instrument)? Promissory estoppel (a promise not to enforce a right)? Res judicata (a previous final judgment)?

Second, if it is estoppel by representation, check all three elements: was there a clear representation of fact? Did the representee rely on it? Did they alter their position as a result?

Third, if it is res judicata, check all four conditions: same parties (or privies)? Same issue? Final judgment? Competent court?

Fourth, consider whether the estoppel can be used offensively or only defensively. In most cases, estoppel is a shield. Note any argument for use as a sword and address why the general rule does not permit this.

Fifth, consider the constitutional dimension. In criminal cases where res judicata or the double jeopardy rule is invoked, engage section 36(9) of the 1999 Constitution alongside the statutory provisions.

Sixth, consider the burden. The party pleading estoppel or res judicata must establish the facts that give rise to it. It is not raised by the court of its own motion. The pleading requirements must be met.

Common Student Mistakes

The first mistake is saying estoppel creates new rights. It does not. It prevents a person from denying a position or enforcing a right inconsistently with what they previously represented. Estoppel is about prevention, not creation.

The second mistake is using estoppel and res judicata interchangeably. Res judicata is a form of estoppel that precludes the court from exercising jurisdiction. Personal estoppel only binds the parties. The distinction affects who can raise the point and what consequences follow.

The third mistake is forgetting the four requirements for res judicata. Students who simply say “the matter was already decided” without addressing sameness of parties, sameness of issues, finality, and competent jurisdiction are giving an incomplete answer.

The fourth mistake is treating promissory estoppel as creating a cause of action. It does not. It can only be used to prevent enforcement of a legal right. It cannot be the sole basis of a claim for damages or specific performance.

The fifth mistake is failing to note that estoppel must be pleaded. It is not a ground that the court raises of its own motion. If the pleadings do not include the facts that give rise to estoppel, the point is lost.

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Footnotes

¹ M Adigun, Estoppel (University of Ibadan Faculty of Law Lecture Slides 2021) slide 2.

² Oyerogba v Olaopa (1998) 12 NWLR (Pt. 578) 353.

³ Adigun (n 1) slide 4.

⁴ Ukaegbu v Ugoji (2002) 7 NWLR (Pt. 766) 419.

⁵ Central London Property Trust v High Trees House Ltd (1947) KB 130.

⁶ McKenny v Chief Constable of West Midlands Police Force (1980) QB 283.